In a wireless communication system, when a mobile station moves from a cell (referring to a base station or a coverage of the base station) to another cell, it is necessary to perform channel switching in order to maintain uninterrupted communication of a mobile user. How to successfully and rapidly complete cell handover is one of important aspects of cellular cell system design in the wireless communication system.
Proximity-based service (ProSe) direct communication, such as device-to-device (D2D) communication, in a cellular network generally refers to a service in which user data can be transmitted directly between terminals without relaying transmission data via the network. In particular, as a typical scenario of Internet of Things applications, D2D communication may include vehicle to vehicle (V2V) communication and the like. The communication resources used by apparatus for the proximity-based service direct communication are allocated by a base station of a current serving cell, so the issue of cell handover should also be considered in the proximity-based service direct communication.